Energy drinks could be a gateway to cocaine use, according to a new study.

Researchers at the University of Maryland School of Public Health found that young adults who said they'd consumed energy drinks yearly between ages 21 and 24 were at greater risk for subsequently doing cocaine, using prescription stimulants for non-medical uses and problem drinking.

The 1,099 study participants were recruited as 18-year-old college students.

Those who didn't consume energy drinks as they got older were less likely to develop substance-abuse problems.

Amelia Arria, director of the university's Center on Young Adult Health and Development, explained that factors contributing to a propensity for risk taking, susceptibility to peer pressure and and changes in energy-drink users' brain that make them like stimulants more.

"Energy drinks are not as regulated as some other beverages. One policy implication is to consider options for regulating the maximum amount of caffeine that can be put in an energy drink." she said. "Parents need to be aware of those risks when their child or adolescent or young adult wants to make a decision about what sort of beverage to consume. They need to be aware of the potential risk."

Energy drinks are a booming segment of the beverage market. Last year, North American retail sales were close to $11 billion, up from less than $5 billion in 2007, according to the market research company Euromonitor.

Anheuser-Busch announced last month that it was acquiring the organic energy drink maker Hiball Energy.

Arria and her co-authors cited existing data that an estimated one in every three American teens and young adults consume energy drinks or energy shots with 50% of college students reporting they've taken them in the past month.

William Dermody, vice president of policy for the American Beverage Association, questioned the methodology and comprehensiveness of the University of Maryland study and said it didn't prove causation.

“Mainstream energy drinks have been extensively studied and confirmed safe for consumption by government safety authorities worldwide, including a recent review by the European Food Safety Authority. Nothing in this study counters this well-established fact," he explained, adding that the U.S. Food and Drug Administration regulates the drinks' ingredients and labeling.

Dermody said that mainstream energy drinks contain about half the caffeine of a similarly-sized cup of coffee shop coffee and that they account for about two percent of Americans' caffeine intake from all sources.